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A term newborn with a right-sided CDH and severe pulmonary hypertension
with systemic hypotension required veno-arterial ECMO. Despite
appropriate cannulas size, high drainage pressure exceeding 60 mmHg was
needed to maintain an ECMO flow at 120 ml/kg/min. Pericardial tamponade
and misplacement of the venous cannula within the azygos vein were
detected. Open thorax surgery was performed, and the cannula was
repositioned. Postoperative X-rays showed an anomalous tip position of
the cannula, suggesting the kinking inside the right atrium (Fig. 1).
Reintervention was needed to restore the cannula. Cannula problems
complicate about 12.8% of all neonatal respiratory
ECMO1. Both cannula malposition and kinking can affect
the proper functioning of the ECMO support, and they should be carefully
ruled out anytime suboptimal venous drainage and insufficient ECMO flow
are experienced2.
Nevertheless, their diagnosis can be challenging, and both X-ray and
echocardiography are essential tools3,4. In
particular, incidental azygos vein cannulation represents a possible
rare ECMO complication in right-sided CDH and should always be kept in
mind in this specific population3. The decision to
reposition or replace the cannula is mandatory, although not risk-free,
in case of inadequate venous drainage or case of possible cardiac or
vessel perforation5.
References
- ELSO. ELSO Registry International Summary . ELSO 2019.
- Mayer A, Raffaeli G, Schena F, et al . Successful extracorporeal
membrane oxygenation after incidental azygos vein cannulation in a
neonate with right-sided congenital diaphragmatic hernia, interruption
of inferior vena cava and azygos continuation. Front Pediatr2019;7:444.
- Thomas TH, Price R, Ramaciotti C, Thompson M, Megison S, Lemler MS.
Echocardiography, not chest radiography, for evaluation of cannula
placement during pediatric extracorporeal membrane oxygenation.Pediatr Crit Care Med 2009;10:56–9.
- Fisher JC, Jefferson RA, Kuenzler KA, Stolar CJ, Arkovitz MS.
Challenges to cannulation for extracorporeal support in neonates with
right-sided congenital diaphragmatic hernia. J Pediatr Surg2007;42:2123–8.
- Byrnes J, Prodhan P, Imamura M, Frazier E. Accidental azygos vein
extracorporeal membrane oxygenation cannulation in a neonate with
premature closure of the ductus arteriosus. ASAIO J2011;57:344–5.